[quote=@DeltaV]
It seems to me like that area shouldn't be frozen at all. 
[/quote]

the whole world is freezing over. That's part of the current lore. And it's also not a natural cold. It's because of the Starless Night. 

Edit: The Starless Night, the death of the gods, the loss of the flames, the freezing world. It affects different places more potently than others. The storm Daen is currently in, which for convenience sake, is called the Everstorm because it never goes away. Isn't natural at all. It's magically constructed.